In conventional manner, a turbojet with afterburning comprises from upstream and downstream in the flow direction of the gas: at least one compressor; a combustion chamber; and at least one turbine with a reheat channel or afterburner chamber.
In general, the afterburner chamber comprises a burner ring that is open in a downstream direction and that has mounted therein a fuel ejector strip that is placed inside an annular thermal protection tube. The ejector strip is connected to fuel feeder means and includes ejector holes pointing downstream and in alignment with holes in the thermal protection tube. A spark plug is mounted on the burner ring and penetrates into the inside of the ring in the proximity of the fuel strip in order to ignite the fuel.
Air-passing orifices are formed in the burner ring and in the upstream wall of the thermal protection tube.
Nevertheless, in the prior art, in the immediate vicinity of the spark plug, the orifices in the burner ring are of diameter that is small compared with the orifices that are further away, and the thermal protection tube does not have any orifices in this location in order to encourage ignition of the afterburner by the spark plug.
In operation, the fuel ejector holes in the vicinity of the spark plug are nevertheless subjected to a fuel coking phenomenon because of the intense heat that exists in this zone, with this phenomenon leading to the fuel ejector holes in the vicinity of the spark plug becoming at least partially clogged and to difficulties or failures in igniting the afterburner chamber.